连词是一种虚词，用于连接单词、短语、从句或句子，在句子中不单独用作句子成分。连词按其性质可分为并列连词和从属连词。
并列连词用于连接并列的单词、短语、从句或句子，如and, but, or, for等；
从属连词主要引出名词性从句(主语从句、宾语从句、表语从句等)和状语从句(时间状语从句、条件状语从句、目的状语从句等)，引出名词性从句的连词如that, whether等，引出状语从句的连词如when, because, since, if 等。
| 英语并列连词的用法 | ||
| 连词用途 | 连词 | 例子 |
| 表示转折关系的并列连词。 | but, yet 等 | Someone borrowed my pen, but I don’t remember who. 有人借了我的钢笔，但我不记得是谁了。 |
| 表示因果关系的并列连词。 | for, so 等 | The child had a bad cough, so his mother took him to the doctor. 这孩子咳得很利害，所以他妈妈带他去看医生。 |
| 表示并列关系的并列连词。 | and , or , either…or , neither…nor | Someone borrowed my pen, but I don’t remember who. 有人借了我的钢笔，但我不记得是谁了。 |
| 英语从属连词的用法 | ||
| 连词用途 | 连词 | 例子 |
| 引导时间状语从句的从属连词 | ||
| 表示“当…时候”或“每当”的时间连词。 | when, while, as, whenever等 | Don’t talk while you’re eating. 吃饭时不要说话。 |
| 表示“在…之前(或之后)”的时间连词。 | before, after | Try to finish your work before you leave. 离开前设法把工作做完。 |
| 表示“在…之前(或之后)”的时间连词。 | before, after | Try to finish your work before you leave. 离开前设法把工作做完。 |
| 表示“自从”或“直到”的时间连词。 | since, until, till | She’s been playing tennis since she was eight. 她从八岁起就打网球了。 |
| 表示“一…就”的时间连词。 | as soon as, the moment, the minute, the second | The moment I have finished I’ll give you a call. 我一干完就给你打电话。 |
| 表示“上次”、“下次”、“每次”等的时间连词。 | every time(每次)，each time(每次)，(the) next time(下次) | You can call me any time you want to. 你随时都可以给我打电话。 |
| 注意：every time, each time, any time前不用冠词，(the) next time, (the) last time中的冠词可以省略，而the first time中的冠词通常不能省略。 | ||
| 引导条件状语从句的从属连词 | ||
| if, unless, as [so] long as, in case | Do you mind if I open the window?我开窗你不介意吧? Don’t come unless I telephone. 除非我打电话，否则你别来。 |
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| 注意：在条件状语从句中，通常要用一般现在时表示将来意义，而不能直接使用将来时态。不过，有时表示条件的 if之后可能用 will，但那不是将来时态, 而是表示意愿或委婉的请求(will为情态动词)。 | ||
| 引导条件状语从句的从属连词 | ||
| in order that, so that, in case, for fear | He raised his voice so that everyone could hear. 他提高了嗓音，以便每个人都能听见。 |
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| 引导结果状语从句的从属连词 | ||
| so that, so…that, such…that | I went to the lecture early so that I got a good seat. 我去听演讲去得很早, 所以找个好座位。 |
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| 引导原因状语从句的从属连词 | ||
| because, as, since, seeing (that), now (that) | He distrusted me because I was new. 他不信任我，因为我是新来的。 |
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| 引导让步状语从句的从属连词 | ||
| although, though, even though, even if, while, however | He bent the iron bar as if it had been made of rubber. 他将铁棍折弯，仿佛那是用橡皮做成的。 |
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| 引导地点状语从句的从属连词 | ||
| where, wherever, everywhere, anywhere | The church was built where there had once been a Roman temple. 这座教堂盖在一座罗马寺庙的旧址。 |
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| 引导比较状语从句的从属连词 | ||
| than和as…as | She was now happier than she had ever been. 现在她比过去任何时候都快活。 |
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| 引起名词从句的从属连词 | ||
| that, whether, if | He replied that he was going by train. 他回答说他将坐火车去。 |
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| 注意：引导名词从句的从属连词主要有that, whether, if 等，它们用于引导主语从句、表语从句、宾语从句和同位语从句。其中that 不仅没不充当句子成分，而且没有词义，在句子中只起连接作用；而 if, whether 虽不充当句子成分，但有词义，即表示“是否”。 | ||
1. in/ by contrast 对比之下
2. unfortunately 不幸地
3. though/ although 尽管
4. even though 即使
5. anyway 无论如何
6. after all 毕竟
7. all the same 依然; 照样
8. in fact/ as a matter of fact 事实上
9. fortunately 幸运地
10. however 然而
11. in spite of 尽管; 虽然
12. at the same time 同时; 然而
13. otherwise 否则
14. on the contrary 相反
15. especially 尤其
16. There are two sides to everything.
有关“承” 的连接词语, 用来承接上下文.
1.by this time 此时
2. at the same time 同时
3. after a while 过了一会儿
4. after a few days 几天以后
5. second/ secondly 第二; 第二点
6. in addition 另外
7. besides/ what’s more 另外
8. by the way 顺便提一句
9. in other words 换句话说
10. in particular/ particularly 特别地
11. worse still 更糟的是
11.in the same way 同样地
12.obviously 明显地
13. no doubt 无疑地
14. for example/ for instance 例如
15. therefore 因此
16. indeed 的确
17. unlike 不象…
18. certainly 当然
19. for another 其次
20. still 仍然
21.similarly 同样地
因果的连接词
therefore
consequently
because of
for the reason
thus
hence
due to
owing to
so accordingly thanks to
on this account;
since;
as;
in this way;
for as a result;
on that account ;
as a consequence